β-carotene triplet state absorption in the near-IR range

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Vol. 91; no. 2; pp. 111 - 115
• Main Author: Bachilo, S.M.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.10.1995; Elsevier Science
• Subjects: Atomic and molecular physics; Carotenoids; Energy transfer; Exact sciences and technology; Infrared spectra; Interconvesion; Molecular properties and interactions with photons; Molecular spectra; Phosphorescence; Physics; Retinoids; Transient absorption; Phosphorescence; Interconvesion; Carotenoids; Retinoids; Transient absorption; Energy transfer; Triplet state; Vibronic states; Excitation energy transfer; Infrared spectra; Absorption spectra; Experimental study; Organic compounds
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/1010-6030(95)04077-S

The β-carotene absorption from the lowest triplet state was investigated over a wide spectral range. A new absorption transition in the near-IR region was found. The absorption band exhibited a 0-0 transition at about 8100 cm −1 with a low intensity, lower by a factor of approximately 300 than the intensity of the known triplet-triplet absorption in the visible range. The vibronic structure of the absorption band was similar to that of the steady state β-carotene absorption. The energy of the triplet state, resulting from this near-IR transition, was close to the β-carotene S 1 state energy. Correspondingly, the interconversion of the carotenoid should depend on the features of this triplet state. Moreover, this relatively low-lying triplet state could also take part in the quenching of molecular triplet states by carotenoids.